Move to C++14 support in ISIS

Look into how the OS's we support (Ubuntu, Fedora, Debian, RHEL/CentOS, MacOS) provide compiler support for C++14 standards.
Make sure these OS's have compiler support for these features, if not, we need to get them for this move.

Try to move ISIS to be compiled with C++14 support.

If all fails, we do not force moving to C++14 support.

Things to consider about this move:
* Do we keep the API C++98 compatible?
* Do we allow the API to use C++14 features?